Ubuntu Manpage: lio_listio - initiate a list of I/O requests

NAME

       lio_listio - initiate a list of I/O requests

LIBRARY

       Real-time library (librt, -lrt)

SYNOPSIS

       #include <aio.h>

       int lio_listio(int mode,
                      struct aiocb *restrict const aiocb_list[restrict],
                      int nitems, struct sigevent *restrict sevp);

DESCRIPTION

The lio_listio() function initiates the list of I/O operations described by the array
aiocb_list.

The mode operation has one of the following values:

LIO_WAIT
The call blocks until all operations are complete. The sevp argument is ignored.

LIO_NOWAIT
The I/O operations are queued for processing and the call returns immediately.
When all of the I/O operations complete, asynchronous notification occurs, as
specified by the sevp argument; see sigevent(3type) for details. If sevp is NULL,
no asynchronous notification occurs.

The aiocb_list argument is an array of pointers to aiocb structures that describe I/O
operations. These operations are executed in an unspecified order. The nitems argument
specifies the size of the array aiocb_list. Null pointers in aiocb_list are ignored.

In each control block in aiocb_list, the aio_lio_opcode field specifies the I/O operation
to be initiated, as follows:

LIO_READ
Initiate a read operation. The operation is queued as for a call to aio_read(3)
specifying this control block.

LIO_WRITE
Initiate a write operation. The operation is queued as for a call to aio_write(3)
specifying this control block.

LIO_NOP
Ignore this control block.

The remaining fields in each control block have the same meanings as for aio_read(3) and
aio_write(3). The aio_sigevent fields of each control block can be used to specify
notifications for the individual I/O operations (see sigevent(7)).

RETURN VALUE

       If mode is LIO_NOWAIT, lio_listio() returns 0  if  all  I/O  operations  are  successfully
       queued.  Otherwise, -1 is returned, and errno is set to indicate the error.

       If  mode is LIO_WAIT, lio_listio() returns 0 when all of the I/O operations have completed
       successfully.  Otherwise, -1 is returned, and errno is set to indicate the error.

       The return status from lio_listio() provides information only about the call  itself,  not
       about the individual I/O operations.  One or more of the I/O operations may fail, but this
       does not prevent other operations completing.  The status of individual I/O operations  in
       aiocb_list  can  be  determined  using aio_error(3).  When an operation has completed, its
       return status can be obtained using aio_return(3).  Individual I/O operations can fail for
       the reasons described in aio_read(3) and aio_write(3).

ERRORS

       The lio_listio() function may fail for the following reasons:

       EAGAIN Out of resources.

       EAGAIN The  number  of I/O operations specified by nitems would cause the limit AIO_MAX to
              be exceeded.

       EINTR  mode was LIO_WAIT and a signal was caught before all I/O operations completed;  see
              signal(7).   (This  may  even  be  one  of  the  signals  used for asynchronous I/O
              completion notification.)

       EINVAL mode is invalid, or nitems exceeds the limit AIO_LISTIO_MAX.

       EIO    One of more of the operations specified by aiocb_list failed.  The application  can
              check the status of each operation using aio_return(3).

       If lio_listio() fails with the error EAGAIN, EINTR, or EIO, then some of the operations in
       aiocb_list may have been initiated.  If lio_listio() fails for any other reason, then none
       of the I/O operations has been initiated.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       ┌───────────────────────────────────────────────────────────────┬───────────────┬─────────┐
       │Interface                                                      │ Attribute     │ Value   │
       ├───────────────────────────────────────────────────────────────┼───────────────┼─────────┤
       │lio_listio()                                                   │ Thread safety │ MT-Safe │
       └───────────────────────────────────────────────────────────────┴───────────────┴─────────┘

STANDARDS

       POSIX.1-2008.

HISTORY

       glibc 2.1.  POSIX.1-2001.

NOTES

       It  is a good idea to zero out the control blocks before use.  The control blocks must not
       be changed while the I/O operations are in progress.  The buffer areas being read into  or
       written  from  must  not be accessed during the operations or undefined results may occur.
       The memory areas involved must remain valid.

       Simultaneous I/O operations specifying the same aiocb structure produce undefined results.